Copper-tin based metal bonds containing abrasives are generally known in the electronics' slicing and dicing industry. As is further known, alloying elements such as nickel, iron, titanium, and molybdenum can be added to the bond mix, to improve the wear resistance of such copper-tin systems for longer wheel life. In addition to improving the wheel life, these alloying elements may also improve the hardness and stiffness of the abrasive structure.
As an alternative to copper-tin bond systems, nickel-based abrasive structures have been used for improved durability and stiffness. For instance, U.S. Pat. No. 3,886,925 discloses a cutting wheel with an abrasive layer formed of high purity nickel electrolytically deposited from nickel solutions having finely divided abrasive suspended in them.
U.S. Pat. Nos. 6,056,795 and 6,200,208 describe abrasive wheels wherein a sintered metal bond includes a metal component such as molybedenum, rhenium, and tungsten (the '795 patent), or an active metal such as titanium, zirconium, hafnium, chromium, and tantalum (the '208 patent), which forms a chemical bond with the abrasive grains on sintering to improve the elastic modulus value of the abrasive wheel. The diamond retention is enhanced due to active metal alloying, leading to improvements in wheel life.
Other characteristics which are desirable in the electronics slicing industry include the ability of the cutting wheel to be self-dressing and operate at lower power. Generally, the self-dressing ability of an abrasive structure can be achieved by matching the wear rate of abrasive to that of the bond. This could be done sometimes through addition of elements such as silver, or by incorporation of soft fillers such as graphite and hexagonal boron-nitride. Another technique is to embrittle the microstructure by adding fillers such as silicon carbide and aluminum oxide, and/or by inducing porosity in the bond. Although such modifications may improve the self-dressing ability of the wheel, other properties of the wheel could be compromised. In this sense, there are a number of non-trivial competing factors that must be considered in the design of abrasive tools.
There is a need, therefore, for metal-based bond systems for abrasive tools that address such factors.